The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected data tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, it is desired that HDDs be able to store more information in their limited area and volume. A technical approach to achieve this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording densities, such as those exceeding 1 Tbit/inch2, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components.
The further miniaturization of the various components presents its own set of challenges and obstacles. For instance, as the recording bit size becomes smaller, the loss of a recording state due to thermal fluctuation is of increasing concern. To compensate for thermal instability associated with small recording bits, a magnetic recording medium with a large coercivity may be used. However, recording to a magnetic recording medium with a large coercivity requires a strong magnetic field, which may exceed the amount of magnetic flux capable of being generated by the magnetic recording head.
Microwave assisted magnetic recording (MAMR) has emerged as a promising magnetic recording technique to address the difficulty in maintaining both the thermal stability and write-ability of a magnetic recording medium. In MAMR, an oscillation element or device is located next to or near the write element in order to produce a high-frequency oscillating magnetic field (in addition to a recording magnetic field emanated from a main pole of the write element), which reduces an effective coercivity of a magnetic recording medium used to store data.
To further achieve higher recording densities using a MAMR head, the recording magnetic field and/or the high-frequency magnetic field generated by the main pole and oscillation device, respectively, may be increased. Unfortunately, configuring the structural characteristics and/or properties of the main pole and elements associated therewith to increase the recording magnetic field may be constrained by the structural characteristics and/or properties of the oscillation device, and vice versa. For instance, one method of increasing the recording magnetic field may involve narrowing the trailing gap positioned between the main pole and the trailing shield of a MAMR head. However, the existence of the oscillation device within the trailing gap renders narrowing the trailing gap to a thickness equivalent to or less than the thickness of the oscillation device problematic or impossible.
There are additional challenges associated with forming and using a MAMR head. For example, formation of the stripe height of the oscillation device may generally involve an etching (e.g., milling) and/or cleaning process that results in a non-uniform thickness of the trailing gap and thus a non-uniform thickness in the oscillation device located within.